The present invention is directed to a mounting assembly for mounting blades to a straw chopper rotor.
Straw choppers are typically provided with rotors having a plurality of blades. The blades may be pivotally mounted to the straw chopper rotor (see DE 36 31 485 C) with screws and flanged nuts. The blades are pivotally mounted to mounts. The mounts are welded to the straw chopper rotor. In order to attain a certain quality of chopper output and to keep the power requirement of the chopper within limits, the blades, are provided with cutting edges on both sides. The blades are disassembled after approximately 100 to 200 hours of operation and reassembled after reversing the blades to use the other cutting edge. After this operating time the blade is dull, as a rule, the length of cut becomes larger and the power requirement increases considerably. After a further 100 to 200 hours of operation the old blades are exchanged for new blades.
The disadvantage of mounting the blades to the mounts by screws and flanged nuts lies in the large amount of time required for changing or reversing the blades. This operation takes approximately four hours for a complete blade exchange for a combine having six straw walkers.
When the mounting assembly is assembled a spring brings the locking element in a trapping position in which it cannot be loosened. In this position the normal operation of the straw chopper is performed. The locking element can be brought into a loosening position by the application of an external force, in which it can be loosened from the pin or fastened to the pin. After the removal of the locking element, the blades can be exchanged or turned around rapidly and without any problems.
In this way the result is that the spring securely traps the locking element during normal operation. In order to attach or exchange the blades, the locking element is brought in a simple way out of the trapping position into the loosening position, in which the locking element can be removed. The pin is removed and the blades can be exchanged or rotated. Following this, the mounting assembly is again attached in reverse order.
The spring pre-loads the pin in the axial direction that is, it applies a force to it that attempts to draw the ends into the holes from which they are projecting. By moving the pin (manually or by means of a tool) against the force of the spring, the locking element can be moved between the trapping position and the loosening position. A Belleville spring or a helical spring can be used. In the illustrated embodiment the spring is in contact with the inner side of the projecting head of the pin that is adjacent to the shank. It would also be conceivable for the spring to act on the pin in an indirect manner, wherein the spring acts on the locking element and pre-loads it into the trapping position. Furthermore, the spring could also be a torsion spring that pre-loads the pin and/or the locking element in the rotary direction into the trapping position.
There are a number of possibilities for the attachment of the locking element to the pin. On the one hand the locking element can be applied to the pin in the radial direction. Thereby when the locking arrangement is brought into the loosening position, the locking element is removed by radially sliding it off the pin. This process can be accomplished without any significant loss of time.
The locking element may be, a cylindrical locking pin that is inserted into a compatible opening in the pin. It can extend with both its ends beyond the pin for trapping the pin in the mounting assembly. In place of a pin, the use of a snap ring is also conceivable, that is inserted into a groove in the pin.
In the trapping position it is appropriate to limit the axial movement of the locking pin (or the snap ring), so that it does not become loosened from the pin in an undesirable manner. For this purpose, the edge of a recess in an element, such as a bushing, could be used to which the locking pin comes into contact.
A bayonet attachment could be used for the blades of the straw chopper, in which the locking element is an element that is rigidly attached to the pin or, particularly for repair purposes, a removable element connected to the pin which can be locked and unlocked by a rotation of the pin only in the loosening position. In the trapping position the element is in contact with a counter bearing. Furthermore, in the trapping position the pin is appropriately secured against a rotation relative to the counter bearing so that an undesirable loosening is not to be feared.
The locking element connected to the pin may be a locking pin extending transverse to the longitudinal axis of the pin, that is inserted in a first rotary position of the pin through the holes and a first groove of a recess in its counter bearing. In a second rotary position of the pin the locking pin is arrested in a second groove of the counter bearing. In order to be able to move the pin between the first and the second rotary position, it must be in the loosening position; in the trapping position no rotation is possible. The counter bearing is preferably arranged in a bushing that is supported in a blade.